TY - JOUR
T1 - A reinvestigation of singlet benzyne thermochemistry predicted by CASPT2, coupled-cluster and density functional calculations
AU - Cramer, Christopher J.
AU - Nash, John J.
AU - Squires, Robert R.
N1 - Funding Information:
This work was supported by the National Science Foundation (CJC and RRS) and the Alfred P. Sloan Foundation (CJC).
PY - 1997/10/10
Y1 - 1997/10/10
N2 - Recent CASPT2 calculations of the heats of formation of the isomeric benzynes by R. Lindh and M. Schütz [Chem. Phys. Lett. 258 (1996) 409] are re-examined. The unrealistically low value reported for p-benzyne (132.7 kcal/mol) is shown to be an artifact of the use of incorrect CASSCF and CASPT2 energies for p-benzyne, as well as a flawed isodesmic reaction analysis. Use of the correct energies and an appropriate isodesmic reaction leads to excellent agreement between the calculated and measured heats of formation for p-benzyne. The performance of coupled-cluster methods and density functional theory in predicting benzyne thermochemistry and singlet-triplet splittings is also evaluated.
AB - Recent CASPT2 calculations of the heats of formation of the isomeric benzynes by R. Lindh and M. Schütz [Chem. Phys. Lett. 258 (1996) 409] are re-examined. The unrealistically low value reported for p-benzyne (132.7 kcal/mol) is shown to be an artifact of the use of incorrect CASSCF and CASPT2 energies for p-benzyne, as well as a flawed isodesmic reaction analysis. Use of the correct energies and an appropriate isodesmic reaction leads to excellent agreement between the calculated and measured heats of formation for p-benzyne. The performance of coupled-cluster methods and density functional theory in predicting benzyne thermochemistry and singlet-triplet splittings is also evaluated.
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U2 - 10.1016/S0009-2614(97)00855-5
DO - 10.1016/S0009-2614(97)00855-5
M3 - Article
AN - SCOPUS:0031563676
SN - 0009-2614
VL - 277
SP - 311
EP - 320
JO - Chemical Physics Letters
JF - Chemical Physics Letters
IS - 4
ER -